Deletion 11q23-->qter (Jacobsen syndrome). Report of three new patients.

Three unrelated patients with de novo del 11q23-->qter are reported. Clinical features included growth and mental retardation, hypotonia, trigonocephaly, facial dysmorphism with hypertelorism, epicanthal folds, abnormally shaped palpebral fissures, eye globe malformations, depressed nasal bridge, "carp-shaped" mouth, highly arched palate, low set and malformed ears. One patient had congenital heart defect, and reduced platelet count. This syndrome, originally reported by Jacobsen, is now corroborated by more than 35 patients and appears as the most common deletion involving 11q. Since deletion of subband 11q24.1 is critical for full expression of this syndrome, the JBS phenotype could be an example of contiguous gene syndrome.